This invention relates a method of making lenses, especially contact lenses, having a colored or tinted portion.
Various colored contact lenses are known in the art. One class of colored lenses includes xe2x80x9ccosmeticxe2x80x9d lenses useful for enhancing or changing the apparent color of the wearer""s iris. Generally, these lenses include a colored iris section, and the colored contact lenses may include an optical correction, for example to accommodate farsightedness or nearsightedness of the wearer of the contact lens, or the contact lenses may be provided with the colored iris section solely for cosmetic purposes. Examples of such contact lenses are disclosed in U.S. Pat. Nos. 5,120,121 and 4,582,402. The colored contact lenses of U.S. Pat. No. 4,582,402 are produced by printing a colored, opaque, intermittent pattern over the iris section of a contact lens. The colored contact lenses of U.S. Pat. No. 5,120,121 are produced by applying a pattern comprised of lens forming mixture doped with a tint to a mold surface, subjecting the mold to polymerization conditions so as to partially or fully polymerize the pattern on the mold surface, dispensing a conventional lens forming monomer mixture which does not contain ink into the mold such that it submerges the previously polymerized pattern, and polymerizing this mixture to obtain a contact lens.
This invention provides a method of making a lens, such as a contact lens, with a colored portion. The method comprises: introducing a lens-forming monomer mixture and a colored material to a lens mold; applying a magnetic field to the monomer mixture and the colored material, whereby the colored material migrates in response to the magnetic field to form a desired pattern; and curing the lens-forming monomer mixture with the colored material forming a desired colored pattern in the lens.
The lens mold may comprise a first mold section including an anterior molding surface and a second mold section including a posterior molding surface, where the lens-forming monomer mixture and the colored material are introduced to a molding cavity formed between the anterior and posterior molding surfaces. After introducing the lens-forming monomer mixture to the first mold section, the second mold section may be assembled with the first mold section to form the molding cavity.
The magnetic field may be generated by placing a magnet adjacent, for example, beneath, the lens mold. The magnet may include a central hole, so as to form an annular colored pattern in the lens generally corresponding to the iris section of the human eye.
Representative colored materials comprise magnetic pigment particles and/or a magnetic dye. Also, the colored material may comprise a mixture of magnetic particles and generally non-magnetic colored particles.